The Wilmington Wave National Weather Service, Wilmington, NC
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The Wilmington Wave National Weather Service, Wilmington, NC VOLUME V, ISSUE II SPRING 2016 INSIDE THIS ISSUE: East Coast Threat: East Coast Threat: The The Submarine Landslide Tsunami 1-2 Submarine - Steve Pfaff Landslide Most people think of tsunamis as a Pacific or Indian Ocean hazard based 1973: The Great Southeastern 3-5 on the devastating tsunamis that oc- Snowstorm curred from the large Dec 26, 2004 Indonesia quake and the March 11, All-Time 2009 Japan earthquake. Although Temperature 6 more tsunamis have occurred in the Extremes Pacific Ocean versus the Atlantic 2016 Atlantic 7 Ocean people along the immediate Hurricane Season U.S. East Coast are at risk too. There are multiple ways in which a tsunami Weather Ready Nation: can form in the Atlantic Ocean, but 8 one type, called a submarine land- Spring & slide tsunami, can develop just off the coast in an area called the Continental Slope Summer Safety (image right). The continental shelf immediately off the shoreline of the U.S. East Surf Zone 9 Coast is characterized by a broad and gradual slope. The location at the edge of the Forecast continental shelf that descends toward the abyssal plain is called the continental Become a slope. The continental slope is characterized by a sharp drop-off, and submarine land- Weather Ready 10 slides occur in this zone. Nation Ambassador During recorded history Weather.gov on there have been tsunamis Your Mobile 11 generated by submarine Phone landslides off the Eastern North American Coast and the most recent one to occur was in Newfoundland in 1929. During this tsunami event over 40 villages were destroyed and 28 people died. It should be noted that the earthquake region that ...Continued from Page 1 would trigger a submarine landslide is limited to the outer shelf and continental slope region as indi- cated by the red dashed area. The United States Geological Survey at Woods Hole has determined that an earthquake less than magnitude 4.5 would not cause enough disruption to generate a subma- rine landslide. Depending on the proximity of the slide to the coast, the tsunami could directly reach the coastline within 1 to 4 hours. High resolution multi-beam bathymetric survey data from the USGS (image on bottom of page 1) has provided researchers with incredible data to better understand the stability of the continental slope, potential impacts, and processes of submarine landslide events. The USGS Woods Hole Research Center high resolution bathymetry data shows evidence of submarine landslides southeast and east of Cape Fear, NC (image below). The slide southeast of Cape Fear oc- curred between 8 and 14 thousand years ago and likely generated a tsunami. Another submarine land- slide off Currituck NC was modeled by the USGS to determine the magnitude of the tsunami it generat- ed. Their models found that waves from a Currituck slump would break approximately 28 miles off- shore and form a tsunami bore wave that continues to propagate toward land. The waves could have been large enough to overtop some of the dunes along the Outer Banks! The National Tsunami Warning Center (NTWC) in Palmer Alaska is responsible for monitoring for tsuna- mi activity that could impact the U.S. East Coast. If an earthquake occurs potentially generating a tsu- nami, then the NTWC would issue a Tsunami Watch, Warning, or Advisory to inform the public. The local NWS offices along the coast would further disseminate the messages to a variety of partners from Emergency Managers and Responders to the United States Coast Guard. Although the probability of a submarine tsunami along the U.S. East Coast is extremely low the impacts they would cause if one occurs would be very high. As a result, coastal counties and several coastal communities across south- east NC and northeast SC are designated as TsunamiReady. These counties/communities have tsunami hazards incorporated into their Emergency Action Plans and participate in yearly tsunami exercises to stay better prepared. P A G E 2 1973: The Great Southeastern Snowstorm - Tim Armstrong If you are a South Carolina native and over the age of 50, chances are you remember the great snow- storm of February 9-11, 1973. This was the single largest snowstorm in history for most locations across the eastern half of South Carolina with all-time snowfall records broken in Florence, Darling- ton, and Columbia. The storm system that brought the record snow to South Carolina began its life as a low pressure cen- ter in the central Gulf of Mexico on February 9, 1973. The low intensified as it crossed Florida during the evening of February 9th and emerged into the Atlantic Ocean on February 10th. Heavy snow began across southern Alabama on the 9th with over a foot reported in the towns of Clayton and Pittsview near the Georgia border. Heavy snow continued across central Georgia on February 10th including 19 inches measured in Thomaston, 16.5 inches in Macon, and 14 inches in Columbus. P A G E 3 ...Continued on Page 4 ...Continued from Page 3 In South Carolina heavy snow occurred across all but the northwestern portion of the state. The highest totals occurred in a region from Bamberg (19 inches) to Manning and Wedgefield (21 inches each) to Florence (17 inches) and Darlington (18 inches). The largest snowfall total came from the Clarendon County town of Rimini where an amazing 24 inches of snow fell! Large snowfall amounts continued into eastern North Carolina including 16.5 inches in Whiteville, 12.5 inches in Wilmington, and 16 inches from Jacksonville to Morehead City. Thunder actually accompanied the snow in locations from Augusta, GA to Florence and into Wilmington. Thundersnow is a very rare occurrence as the air must be cold enough at the surface to allow snow to fall, yet much colder still aloft to produce the instability thunderstorms need. About 30,000 tourists traveling to or from Florida and more northern states were stranded on the State's high- ways. Many were rescued by helicop- ter and some by other vehicles. When the hotels and motels were filled, they were housed in armories, schools, and churches. Farmers gave aid to travelers stranded near their homes. Many farm homes had 50 to 60 unexpected guests for a day or two." The snow was ac- companied by strong winds and fol- lowed by severe cold. Drifts up to 7 or 8 feet could be found in same locations and all highways in the central part of the State were closed for from 2 to 4 days. Many tons of food and supplies were airlifted by helicopter to snowed- in families. At least 200 buildings col- lapsed, as did thousands of store awn- Weather Map from February 10, 1973 at 7 AM. Snow was falling from ings and carports..." Florida to North Carolina as low pressure intensified off the coast. -South Carolina State Climatologist Impacts from this storm were severe and long-lasting. Towns and cities were isolated for many days from Alabama to North Carolina as virtually all roads were completely impassable. Road crews could not keep the interstate system open either; approximately 200 miles of I- 75 was closed across Georgia as was a large section of I-95 south of Fayetteville, NC. Many thousands of vehicles were stranded and abandoned as people sought shelter from the cold and snow. The Sumter Daily Item reported at least 11 exposure-related fatalities across South Carolina. Traffic accidents claimed additional lives in Louisiana and Georgia, and in North Carolina a small airplane crashed during the storm killing two and injuring three. P A G E 4 ...Continued on Page 5 ...Continued from Page 4 In 1973 the National Oceanic and Atmospheric Administration hadn’t started the GOES weather satel- lite program. NASA however was orbiting a weather satellite named Applications Technology Satellite 3, or ATS-3, which observed the storm and sent back amazing photos. We contacted the Space Science and Engineering Center at the University of Wisconsin and were able to get scanned images of this sat- ellite data sent to us. Here, are a few of the images. Additional details about this historic event including satellite loops, weather maps, and first-hand accounts of the storm are available on our webpage at http://www.weather.gov/ilm/Feb1973Snow Coastal Carolinas AMS/NWA Local Chapter Calling all local weather enthusiasts!! Did you know that there’s a new local chapter of the American Meteorolog- ical Society & National Weather Association chapter?! The Coastal Carolinas AMS/NWA chapter is still fairly new, as they were founded in 2013. The group is comprised of National Weather Service, media, and private sector meteorologists, as well as local area students, retirees, and weather enthusiasts. From Myrtle Beach, SC to Wil- mington, NC, the chapter is gradually growing, and while a majority of their interests lie within this area, anyone across the Carolinas is welcome. Anyone with an interest in weather is encouraged to attend and participate as meetings are held throughout the year across the area. For more information at the chapter, as well as upcoming meeting information, visit: www.ametsoc.org/chapters/coastalcarolinas P A G E 5 All-time Temperature Extremes - Tim Armstrong How hot and cold has it ever been here in the eastern Carolinas? We’ve searched through our record books to find the all-time extremes for a number of cities in our area. HOTTEST ON RECORD Wilmington, NC Whiteville, NC Elizabethtown, NC Lumberton, NC Southport, NC 104° 105° 105° 108° 103° on June 27, 1952 on August 9, 2007 on August 11, 2007 on July 21, 1926 on June 26, 1952 Florence, SC Myrtle Beach, SC Darlington, SC Georgetown, SC Dillon, SC 108° 104° 109° 106° 107° on June 27, 1954 on August 5, 1954 on September 4, 1925 on June 30, 1990 on June 28, 1954 COLDEST ON RECORD Wilmington, NC Whiteville, NC Elizabethtown, NC Lumberton, NC Southport, NC 0° -2° -3° -2° -3° on December 25, 1989 on December 25, 1989 on December 25, 1989 on December 25, 1989 on December 25, 1989 Florence, SC Myrtle Beach, SC Darlington, SC Georgetown, SC Dillon, SC 0° 7° -4° 4° -1° on January 21, 1985 on January 16, 1994 on January 21, 1985 on February 14, 1899 on January 21, 1985 P A G E 6 2016 Atlantic Hurricane Season Begins June 1st - Sandy LaCorte In just under the two months, the 2016 Atlantic Hurricane Season will begin.